Novel peptides which are active on the central nervous system and have an action on the cholinergic system

ABSTRACT

The invention relates to peptides of the formula I 
     
         R.sup.4 -A.sup.5 -A.sup.6 -A.sup.7                         (I) 
    
     in which R 4  denotes an acyl group, R 5  denotes D-Lys or Lys, A 6  denotes the radical of phenylalanine, N-methylphenylalanine, 4-alkoxyphenylalanine or 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, and R 7  denotes a basic radical, processes for their preparation and their use.

This is a division of application Ser. No. 663,193, filed Oct. 22, 1984U.S. Pat. No. 4,623,715.

We have observed that even simple dipeptide derivatives, such as, forexample,

    Z-Lys-Phe-OMe                                              (IV)

(Z=benzyloxycarbonyl) cause the urge to groom and move in rats followingintracerebroventricular (i.c.v.) administration of 10 μg. At the sametime, cholinergic mechanisms in the central nervous system (CNS) areinfluenced. In the striatum of rats, the choline content is reduced andthe acetylcholine content is increased following subcutaneousadministration of 10 μg.

The effects are intensified if the carboxyl group carries a radical withbasic substituents, it being possible for lysine to be in the D-form.Thus, for example, compound V

    Z-D-Lys-Phe-NH-(CH.sub.2).sub.8 -NH.sub.2.2HCl             (V)

already shows the same actions on i.c.v. or s.c. administration of 1 μg.

The effects described are characteristic of ACTH and MSH.

When the Z radical in V was replaced by phenylalanine and the α-aminogroup thereof was substituted by partial sequences of ACTH/MSH or byother acyl, aminoacid and peptide radicals, it was possible to observe afurther increase in the effects in the cholinergic system, the urge togroom and move being weakened.

With the compounds of higher activity, not only an increased but also areduced level of acetylcholine is observed. Both effects indicate anincreased synthesis rate or an increased conversion.

An acceleration in the acetylcholine conversion in various areas of thebrain following intracerebroventricular (i.c.v.) administration ofalpha-MSH, ACTH and longer-chain ACTH fragments (ACTH 1-24) has alreadybeen described earlier by two study groups (P. Wood et al.: LifeSciences, 22 (1978), 673-678; JPET, 209 (1979), 97-103; L. J. Botticelliand R. J. Wurtmann: Brain Research 210 (1981), 479-484; and J.Neuroscience 2 (1982), 1316-1321).

ACTH-like short peptides which are known from Ann. N.Y. Acad. Sci. 297(1977) 267-274 also have a neurotropic action.

In the abovementioned attempts to increase the action, it was found thatthe nature of the N-terminal substituents is less important than thesubstitution per se, especially when the substituents are peptides. Thephenylalanines can also be modified without a loss in action. It wasfurthermore found that the C-terminal basic substituent always increasesthe action by about a 100-fold in comparison with an unsubstitutedcompound.

The invention thus relates to compounds of the general formula I

    R.sup.4 -A.sup.5 -A.sup.6 -A.sup.7                         (I)

in which:

R⁴ denotes benzyloxycarbonyl (Z), (C₂ -C₆)-alkanoyl, (C₆ -C₁₀)-aryl-(C₂-C₄)-alkanoyl or cycloalkanoyl with up to 2 alkyl and 5-7 cycloalkylcarbon atoms, bonded via N.sub.α, or

R³ -A⁴, in which

A⁴ represents the radical of a neutral aliphatic or aromatic α-aminoacidand

R³ represents hydrogen, Z, (C₂ -C₆)-alkanoyl, (C₆ -C₁₀)-aryl-(C₂-C₄)-alkanoyl or cycloalkanoyl with up to 2 alkyl and 5-7 cycloalkylcarbon atoms, bonded via N.sub.α, or

R² -A³ -A⁴, in which

A⁴ is as defined above,

A³ denotes His, Ala, Phe or D-Lys and

R² is defined as R³, or represents (C₂ -C₄)-alkanoyl-ω-amino-(C₅-C₈)-n-alkanoyl, methylsulfonyl-ω-amino-(C₅ -C₈)-n-alkanoyl,4-methylsulfonylbenzoyl, succinoyl or glutaroyl, bonded via N.sub.α, or

R¹ -A² -A³ -A⁴, in which

A³ and A⁴ are as defined above,

A² represents pyroglutamyl, Glu, D-Glu or Ala and

R¹ is defined as R², or represents (C₂ -C₄)-alkanoyl-ω-amino-(C₃-C₄)-n-alkanoyl, methylsulfonyl-ω-amino-(C₃ -C₄)-n-alkanoyl,methylamidoglutaroyl, H-Met, H-D-Met, H-Met(O), H-D-Met(O), H-Met(O₂),H-D-Met(O₂), H-Gly, Z-Gly, H-Tyr, Z-Tyr or pyroglutamyl, bonded viaN.sub.α,

A⁵ denotes D-Lys or Lys,

A⁶ denotes the radical of phenylalanine, N-methylphenylalanine, 4-(C₁-C₄)-alkoxyphenylalanine or 1,2,3,4-tetrahydroisoquinoline-3-carboxylicacid and

R⁷ denotes NH-(CH₂)_(n) -NH₂, Gly-NH-(CH₂)_(m) -NH₂, Gly-Lys-R⁸ orGly-D-Lys-R⁸, in which n represents an integer from 4 to 10, mrepresents an integer from 2 to 6 and R⁸ represents 1-pyrrolidinyl,1-piperidinyl, NH-R or NR₂, where R=(C₁ -C₄)-alkyl,

and physiologically acceptable salts thereof.

R⁴ preferably denotes Z, phenyl-(C₂ -C₄)-alkanoyl, (C₂ -C₆)-alkanoyl orR³ -A⁴.

A⁴ can denote, for example, the radical of an aliphatic aminoacid, suchas Ala, Val, Leu, Ile or Met, of a substituted aliphatic aminoacid, suchas Ser(C₁ -C₆ -alkyl), Thr(C₁ -C₆ -alkyl) or Cys(C₁ -C₆ -alkyl), of anaromatic aminoacid, such as Phe or Phg (C-phenylglycine), or of asubstituted aromatic aminoacid, such as Tyr(C₁ -C₆ -alkyl). Advantageousradicals are those of, for example, Ala, Val, Leu, Ile, Phe, Tyr(Me) andTyr(Et), in particular Phe, Ala and Leu, Phe being particularlypreferred.

R³ preferably represents hydrogen, Z, phenyl-(C₂ -C₄)-alkanoyl or (C₂-C₆)-alkanoyl.

R² preferably has the abovementioned meanings of R³ or isacetyl-ε-aminocaproyl, methylsulfonyl-ε-aminocaproyl,4-methylsulfonylbenzoyl or glutaroyl.

Preferred meanings of R¹ are the preferred meanings of R² andacetyl-β-alanyl, methylsulfonyl-β-alanyl, methylamidoglutaroyl, H-Met,H-Met(O), H-D-Met(O), H-Met(O₂), H-Gly, Z-Gly, H-Tyr, Z-Tyr andpyroglutamyl, H-Met(O), H-Met(O₂) and HO₂ C-(CH₃)₃ CO- are particularlypreferred. The invention relates further to compounds with theR-configuration and to compounds with the S-configuration of thesulfinyl group of the radical H-Met(O)-.

A⁵ is preferably D-Lys.

A⁶ can denote, for example, the radical of phenylalanine,N-methylphenylalanine, 4-methoxyphenylalanine, 4-ethoxyphenylalanine or1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid, the L-configurationbeing preferred in each case; Phe is particularly preferred.

The nature of the basic C-terminal radical R⁷ is not critical. Radicalssuch as -NH-(CH₂)_(n) -NH₂ have proved advantageous, n preferably being6-10, in particular 8.

Some part sequences of preferred pentapeptide and hexapeptidederivatives are mentioned below: -Glu-His-Phe-D-Lys-Phe,-Ala-Ala-Phe-D-Lys-Phe- and -Glu-Ala-Phe-D-Lys-Phe-.

The following compounds of the formula I are particularly preferred:H-Met(O)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂ andH-Met(O)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₆ -NH₂, in each case with thesulfonyl group in the S- or R-configuration,H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂,H-Met(O₂)-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂ and HOOC-(CH₂)₃-CO-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.

The invention furthermore relates to a process for the preparation ofcompounds of the formula I, which comprises condensing a fragment withan N-terminal free amino group with a fragment with a C-terminal freecarboxyl group, the primary and secondary amino groups in thesefragments which do not participate in the reaction being protected witha protective group of the urethane type which can be split off underacid conditions (such as, for example, Boc), and the carboxyl groups inthese fragments which do not participate in the reaction being protectedwith protective groups of the ester type which can be split off underacid conditions (such as, for example, Bu^(t)), splitting off in theresulting compounds, under acid conditions, the protective groupsintroduced to protect amino or carboxyl groups, and, if appropriate,converting the compounds into their physiologically acceptable salts.

Protective groups of the urethane type are described in Schroder, Lubke,The Peptides, Vol. I, New York, London 1965, page 22 et seq., and thoseof the ester type are described in loc.cit., page 52 et seq.

The process is advantageously carried out by

    ______________________________________                                        (a) condensing a compound of the formula IIa with                             a compound of the formula IIIa                                                R.sup.4 --A.sup.5 --OH                                                                       H--A.sup.6 --R.sup.7                                           (IIa)          (IIIa)                                                         (b) condensing a compound of the formula IIb with                             a compound of the formula IIIb                                                R.sup.4 --OH   H--A.sup.5 --A.sup.6 --R.sup.7                                 (IIb)          (IIIb)                                                         (c) condensing a compound of the formula IIc with                             a compound of the formula IIIc                                                R.sup.3 --OH   H--A.sup.4 --A.sup.5 --A.sup.6 --R.sup.7                       (IIc)          (IIIc)                                                         (d) condensing a compound of the formula IId with                             a compound of the formula IIId                                                R.sup.2 --OH   R--A.sup.3 --A.sup.4 --A.sup.5 --A.sup.6 --R.sup.7             (IId)          (IIId)                                                         (e) condensing a compound of the formula IIe with                             a compound of the formula IIIe                                                R.sup.1 --OH   H--A.sup.2 --A.sup.3 --A.sup.4 --A.sup.5 --A.sup.6                            --R.sup.7                                                      (IIe)          (IIIe)                                                         ______________________________________                                    

in which the radicals R¹ -R⁴, R⁷ and A² -A⁶ have the meanings defined inclaim 1, but free primary and secondary amino groups, excluding theN-terminal groups of the compounds of the formulae IIIa-e, are protectedwith acid groups of the urethane type which can be split off under acidconditions, and free carboxyl groups, with the exception of theC-terminal groups of the compounds of the formulae IIa-e, are protectedwith protective groups of the ester type which can be split off underacid conditions, and then, in the compounds obtained according to(a)-(e), splitting off, under acid conditions, the protective groupsintroduced to protect the amino or carboxyl groups and, if appropriate,converting the resulting compounds into their physiologically acceptablesalts. The reaction of compounds of the formula IIb with compounds ofthe formula IIIb is preferred.

The starting compounds of the formulae IIa-e and IIIa-e are known, orthey are accessible in a manner which is known per se, for example byfragment condensation.

In the synthesis of the peptides according to the invention, thebenzyloxycarbonyl or 9-fluorenylmethoxycarbonyl radical is preferred asthe N.sup.α -protective group, and the tert.-butyl radical is preferredas the carboxyl-protective group.

The condensation in the process according to the invention is carriedout by the general methods of peptide chemistry, in the case of sulfonylcompounds via the sulfonyl chloride, and otherwise preferably by themethod of mixed anhydrides, via active esters or azides, or by thecarbodiimide method, in particular with the addition of substances whichaccelerate the reaction and prevent racemization, such as, for example,1-hydroxybenzotriazole, N-hydroxysuccinimide,3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine andN-hydroxy-5-norbornene-2,3-dicarboximide, and furthermore usingactivated derivatives of 1-hydroxybenzotriazole or anhydrides ofphosphoric, phosphonic and phosphinic acids.

Solvents are dimethylformamide, dimethylacetamide, hexamethylphosphoricacid triamide, N-methylpyrrolidone or dimethylsulfoxide. If thesolubility of the components allows, solvents such as methylene chlorideor chloroform can also be used. The methods mentioned are described, forexample, in Meienhofer-Gross: "The Peptides", Academic Press, Vol. I,(1979).

The action of the compounds according to the invention on thecholinergic system is determined by a method described in J. Neurochem.20 (1973), pages 1-8.

Some characteristic examples are listed in the following Table, whichshows, inter alia, the increase in action of the peptides according tothe invention containing basic substituents in comparison with ACTH andshorter unsubstituted peptides.

The compounds according to the invention effect a significant,dose-dependent weakening of the amnesia induced by electric shock orscopolamine in mice ("one-trial passive avoidance test"). For compoundIX, for example, the minimum effective dose required is 0.03 μg/kg,following s.c. administration.

In humans, the peptides according to the invention have amood-lightening, antidepressant and anxiolytic action. They increaseattention to the environment, improve the learning and memoryperformance, have a favorable effect on resocialization processes andcan be used for all diseases of post-traumatic and degenerative braindamage which are associated with a reduced central acetylcholinemetabolism function, for example mild dementia and also earlymanifestations of Alzheimer's disease and the like.

The compounds according to the invention are used as medicaments in theform of their salts with physiologically acceptable acids, such as, forexample, acetic acid, malonic acid, citric acid or malic acid, or as thehydrochloride or sulfate, if they are not present in the form of Zwitterions. In the case of an adult of normal weight, intranasaladministration is preferably effected in a dosage of 0.1 μg to 1 mg perdose, particularly preferably 1 to 500 μg and especially 5 to 200 μg perdose. The medicaments according to the invention can be administered,for example, up to 6 times, preferably up to 3 times, per day. In manycases, administration of one dose per day is also sufficient. Thecompounds according to the invention can also be administeredsubcutaneously in amounts of 0.001 to 10 μg/kg, preferably 0.01 to 5μg/kg and in particular 0.05 to 2 μg/kg.

    __________________________________________________________________________                                                       Biochemical effects                                                           in                                                                            the striatum                                                       Behavior   Dose                                                               (Grooming, yawning,                                                                      mcg/kg                     Compound                                stretching)                                                                              s.c.;                      No. Comparison substances:              (10 μg i.c.v.)                                                                        (rats)                                                                             ACH CH                __________________________________________________________________________    VI  ACTH-(1-24)                         ++         0.01-1                                                                             ↓                                                                          ↑           VII Met--Glu--His--Phe--Arg--Trp--Gly--OH                                                                             φ      10-1000                                                                            ↑                                                                           ↓          VIII                                                                              Met(O)--Glu--His--Phe--D-Lys--Phe--OH                                                                             φ      0.3-1                                                                              ↓                                                                          ↑           IX  Met(O)--Glu--His--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.8 --NH.sub.2                                                (+)        0.01 ↓                                                                          ↓          X   Met(O.sub.2)--Glu--His--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.8                 --NH.sub.2                          φ      0.01 ↓                                                                          ↓          XI  H--Met(O.sub.2)--Ala--Ala--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.8              --NH.sub.2                                     0.01 ↑                                                                           ↓          XXII                                                                              HOOC--(CH.sub.2).sub.3 --CO--Glu--Ala--Phe--D-Lys--Phe--NH--(CH.sub.8)        --NH.sub.2                                     0.01 ↓                                                                          ↓          XIII                                                                              H--Met(O.sub.2)--Glu--Ala--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.8              --NH.sub.2                                     0.1  ↑                                                                           ↓          XIV H--Tyr--Glu--His--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.3 --NH.sub.2                                                +          0.1  ↑                                                                           ↓              Z--D-Lys--Phe--NH--(CH.sub.2).sub.3 --NH.sub.2 1.0  ↑                                                                           ↓          XVI pyro--Glu--Glu--His--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.8 --NH.sub.2                                                        0.1  ↑                                                                           ↓          XIII                                                                              N--Met(O)--Glu--His--Phe--D-Lys--Phe--NH--(CH.sub.2).sub.6 --NH.sub.2                                                        0.01 ↓                                                                          ↓          __________________________________________________________________________     ACH = acetylcholine                                                           CH = choline                                                             

Depending on their structure, they can be absorbed perorally to agreater or lesser degree. The comparatively wide dosage range forperoral administration is between 0.1 and 50 mg daily, divided overseveral administrations. The preferred individual dose for the compoundswith the most potent action is 0.1 to 10 mg.

The compounds according to the invention can be administered orally orparenterally in a corresponding pharmaceutical formulation. For an oraluse form, the active compounds are mixed with the additives usual forthis purpose, such as excipients, stabilizers or inert diluents, and arebrought into suitable forms of administration, such as tablets, coatedtablets, push-fit capsules, aqueous alcoholic or oily suspensions oraqueous alcoholic solutions, by customary methods. Inert excipientswhich can be used are, for example, gum arabic, magnesium carbonate,potassium phosphate, lactose, glucose and starch, especially cornstarch. The compounds can be formulated either as dry granules or moistgranules. Examples of possible oily excipients or solvents are vegetableand animal oils, such as sunflower oil or cod liver oil.

For subcutaneous or intravenous administration, the active compounds orphysiologically acceptable salts thereof are dissolved, suspended oremulsified, if desired with the substances customary for this purpose,such as solubilizing agents, emulsifiers or other auxiliaries. Examplesof possible solvents for the novel active compounds and thecorresponding physiologically acceptable salts are: water, physiologicalsaline solutions and alcohols, for example ethanol, propanediol andglycerol, and in addition also sugar solutions, such as glucose ormannitol solutions, or a mixture of the various solvents mentioned.

EXAMPLES

The abbreviations used in peptide chemistry are used in the followingpreparation examples.

Other frequently used abbreviations are:

DMF--dimethylformamide

NEM--N-ethylmorpholine

DCC--dicyclohexylcarbodiimide

DCU--dicyclohexylurea

DCA--dicyclohexylamine

HOBt--1-hydroxybenzotriazole

HOObt--3-hydroxy-4-oxo-3,4-dihydro-1,2,3-benzotriazine

Z--benzyloxycarbonyl

Boc--tert.-butoxycarbonyl

Bu^(t) --tert.-butyl

Me--methyl

Et--ethyl

Tic--1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (L-form)

HONp--4-nitrophenol

HOTcp--2,4,5-trichlorophenol

HONSu--N-hydroxysuccinimide

TLC--Thin layer chromatography/thin layer chromatogram in the eluents:

A: methyl ethyl ketone:pyridine-water-acetic acid (70:15:15:2)

B: n-butanol:acetic acid:water (6:2:2)

C: n-butanol:pyridine:acetic acid:water (4:1:1:5) from this the upperphase

D: heptane:tert.-butanol:pyridine (3:1:1)

EXAMPLE 1 Z-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl (a) Boc-NH-(CH₂)₈ -NH-Boc

65 g of 1,8-diaminooctane are dissolved in 800 ml of dioxane and 400 mlof water. 69 ml of triethylamine are added, and 216 g of di-tert.-butyldicarbonate are then added in portions at below 20° C., withvibromixing, the reaction product already precipitating. The mixture issubsequently stirred for 2 hours and the precipitate is filtered off,washed with a little water and dried. The filtrate is concentrated invacuo, a precipitate being filtered off several times with suction andtreated as above. The precipitates are collected, digested in water anddried.

Yield: 118 g of melting point 103°-104° C.

C₁₈ H₃₆ N₂ O₄ (344.4).

Calculated: C 62.75, H 10.53, N 6.97. Found: C 63.0, H 10.7, N 7.2.

(b) Boc-NH-(CH₂)₈ -NH₂.HCl

68 g of the compound prepared according to (a) are suspended in 1 literof dry ether containing 2N HCl. The suspension is stirred at roomtemperature for 3 hours and cooled to about 0° C. and the precipitate isfiltered off and washed with dry ether.

Yield: 38 g, melting point: 150°-152° C. (decomposition).

C₁₃ H₂₉ ClN₂ O₂ (280.8).

Calculated: 55.65, H 10.4, N 10.0, Cl 12.6. Found: C 55.6, H 10.5, N10.2, Cl 12.5.

(c) Z-D-Lys(Boc)-Phe-OMe

43.2 g of Z-D-Lys(Boc)-OH, prepared analogously to the L-compound, aredissolved in 400 ml of dimethylformamide. 24.5 g of H-Phe-OMe.HCl, 15.33g of HOBt, 14.53 ml of NEM and, with stirring, 25 g of DCC are added,and the mixture is left to stand overnight at room temperature. Afterthe urea has been filtered off, the solvent is distilled off in vacuoand the oily residue is recrystallized from 200 ml of 80% strengthethanol.

Yield: 57.9 g (94% of theory).

For analysis, a sample is precipitated from DMF with ether/petroleumether (1:1) and crystallized again from 80% strength ethanol.

C₂₉ H₃₉ N₃ O₇ (541.6).

Calculated: C 64.31, H 7.26, N 7.76. Found: C 64.3, H 7.3, N 7.5.

[α]_(D) ^(20:) +5.5° (c=0.5 in 90% strength acetic acid).

(d) Z-D-Lys(Boc)-Phe-OH

56.0 g of the methyl ester are dissolved in a mixture of 500 ml ofdioxane, 200 ml of methanol and 60 ml of water, under the influence ofheat, and are hydrolyzed at pH 12.5 with 1N NaOH in the course of 150minutes. The pH is brought to 7 with 2N HCl, with stirring, most of theorganic solvent is distiled off in vacuo, irrespective of theprecipitate, 800 ml of ice-cold ethyl acetate are added, and 35 ml of 2NHCl are carefully added, with ice-cooling and vigorous stirring. Thelayers are separated and the ethyl acetate solution is washed with alittle water, dried over sodium sulfate and concentrated in vacuo. Aftersome time, the initially oily residue crystallizes completely and thecrystals are washed with petroleum ether and dried in vacuo.

Yield: 50.2 g (92%). Melting point: 85°-87° C.

C₂₈ H₃₇ N₃ O₇ (527.6).

Calculated: C 63.74, H 7.09, N 7.96. Found: C 63.3, H 7.3, N 8.4.

[α]_(D) ^(20:) +10.7° (c=1 in 90% strength acetic acid).

(e) Z-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

48.5 g of the dipeptide prepared according to (d) and 25.8 g of theBoc-diamine hydrochloride prepared according to (b) are dissolved in 1liter of DMF. 40.8 g of HOObt, 15 ml of NEM and, with cooling, 22.5 g ofDCC are added in succession and the mixture is stirred for 1 hour andleft to stand overnight at room temperature. The urea is filtered off,the solvent is distilled off in vacuo and the residue is recrystallizedfrom 300 ml of 80% strength ethanol. The precipitate can be filtered offonly with difficulty and is advantageously obtained by centrifugation.

Yield: 60.2 g (86.9%).

C₄₁ H₆₂ N₅ O₈ (753.0).

Calculated: C 65.40, H 8.30, N 9.3. Found: C 65.6, H 8.5, N 9.3.

[α]_(D) ^(20:) +2.0° (c=1 in 90% strength acetic acid).

(f) Z-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

753 mg of the compound obtained according to (e) are left to stand in7.5 ml of concentrated HCl/water/formic acid (0.6:0.6:9.6) for 30minutes. The solvent is distilled off in vacuo and subsequentdistillation with toluene is carried out. The residue solidifies onstanding under ether, and is filtered off, washed with ether and driedin vacuo over KOH.

Yield: 650 mg.

In the TLC on silica gel in eluent A, the compound is a single compound.

The elementary analysis is within the limits of error.

EXAMPLE 2 Z-D-Lys-Phe-OMe.HCl

Analogously to Example 1f, the Boc group of 1.0 g ofZ-D-Lys(Boc)-Phe-OMe, prepared according to Example 1c, is split off.

Yield: 820 mg, a single compound in the TLC (A), elementary analysiscorrect.

EXAMPLE 3 Z-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

The Boc group of 1.2 g of the Boc-protected L-compound preparedanalogously to Example 1e is split off as described above.

Yield: 0.98 g, single compound in the TLC (A), elementary analysiscorrect.

EXAMPLE 4 Z-Lys-Tic-NH-(CH₂)₈ -NH₂.2HCl (a) Z-Lys (Boc)-Tic-OMe

15.2 g of Z-Lys(Boc)-OH and 9.1 g of H-Tic-OMe.HCl, prepared from theanimoacid (J. Am. Chem. Soc. 70 (1948), page 182) with methanol/SOCl₂ ina known manner, are reacted with 5.4 g of HOBt, 5.5 ml of NEM and 8.8 gof DCC in 300 ml of DMF analogously to Example 1e. The oil which remainsafter filtering off the urea and distilling off the DMF in vacuo istaken up in 200 ml of ethyl acetate and the solution is washed with 10%strength aqueous citric acid, 1M KHCO₃ solution and water in succession,dried over Na₂ SO₄ and evaporated in vacuo. The residue becomesfoam-like on drying in vacuo, but does not crystallize.

Yield: 21.1 g.

(b) Z-Lys(Boc)-Tic-OH

17.9 g of the methyl ester prepared according to (a) are hydrolyzedanalogously to Example 1. d After working up and distilling off theethyl acetate, a noncrystallizing oil remains.

Yield: 15.9 g. A single compound in the TLC (A).

C₂₉ H₃₇ N₃ O₇ (539.64).

Calculated: C 64.55, H 6.91, N 7.79. Found: C 63.9, H 6.9, N 7.9.

(c) Z-Lys(Boc)-Tic-NH-(CH₂)₈ -NH-Boc

2.16 g of the compound described under (b) are reacted with 1.12 g ofBoc-diamine hydrochloride, 0.54 g of HOBt, 0.7 ml of NEM an 0.9 g of DCCanalogously to Example 1e. The crude product is taken up in ethylacetate and washed analogously to (a). After the solvent has beendistilled off, a non-crystallizing oily residue is obtained.

Yield: 2.73 g. A single compound in the TLC (A), apart from a trace ofDCU.

(d) Z-Lys-Tic-NH-(CH₂)₈ -NH₂.2 HCl

The Boc group is split off from 1.1 g of the compound prepared accordingto (c) in 10 ml of reagent according to Example 1f. The product is notcrystalline. Yield: 0.61 g. Almost a single compound in the TLC (B, C).

EXAMPLE 5 Z-D-Lys-Tic-NH-(CH₂)₈ -NH₂.2HCl

The compound is obtained analogously to Example 4. It is also notcrystalline and is essentially a single compound in the TLC (B, C).

EXAMPLE 6 Z-Lys-Tic-OMe. HCl

Analogously to Example 1f, the Boc gorup is split off from 0.7 g of thecompound obtained according to Example 4a. The residue is dissolved inwater and the solution is filtered and freeze-dried. White powder.Yield: 0.43 g. Almost a single compound in the TLC (B, C).

EXAMPLE 7 Z-D-Lys-Phe-D-Lys-Phe-Gly-NH-(CH₂)₄ -NH₂.3HCl (a)Z-D-Lys(Boc)-Phe-Gly-OME

1.26 g of G-Gly-OMe.HCl, 1.6 g of HOObt, 1.3 ml of NEM and 2.2 g of DCCare added in succession, with stirring, to 5.3 g of Z-D-Lys(Boc)-Phe-OH(Example 1d) in 60 ml of DMF. After the mixture has been left to standovernight, the urea is filtered off and the filtrate is concentrated invacuo. The residue is taken up in 200 ml of ethyl acetate and thesolution is washed in the cold with 10% strength citric acid solution,saturated sodium bicarbonate solution and water and concentrated invacuo to about 40 ml, and ether/petroleum ether 1:1 are added to theresidue. The precipitate is filtered off, washed with ether/petroleumether 1:1 and dried.

(b) H-D-Lys(Boc)-Phe-Gly-OME, TosOH

4.21 g of the compound obtained according to (a) are subjected tocatalytic hydrogenation on Pd in 70 ml NeOH, with titration with 1Nmethanolic TosOH at pH 4.5. After the catalyst has been filtered off,the solvent is distilled off in vacuo and the residue is trituratedseveral times with diisopropyl ether and dried.

Yield: 3.82 g, a single compound in the TLC (A, C).

(c) Z-D-Lys(Boc)-Phe-D-Lys(Boc)-Phe-Gly-OMe

1.6 g of HOOBt, 1.3 g of NEM and 2.2 g of DCC are added to 5.3 g ofZ-D-Lys(Boc)-Phe-OH and 6.4 g of H-D-Lys(Boc)-Phe-Gly-OMe, TosOH in 100ml of DMF, with stirring. After the mixture has been left to standovernight and the urea has been filtered off, the solvent is distilledoff in vacuo. The residue is taken up in 300 ml of ethylacetate/n-butanol (2:1), the mixture is washed, as above, with citricacid solution, sodium bicarbonate solution and water and dried oversodium sulfate and the solvent is distilled off in vacuo. The residue isrecrystallized from 60 ml of isopropanol.

Yield: 7.0 g, a single compound in the TLC (A).

(d) Z-D-Lys(Boc)-Phe-D-Lys(Boc)-Phe-Gly-OH

5.4 g of the methyl ester are dissolved in 50 ml of dioxane+50 ml ofmethanol+20 ml of water, under the influence of heat, and are hydrolyzedat pH 13 with 1N NaOH. The pH is brought to 6 with 2N HCl in the cold,most of the solvent is distilled off, 100 ml of ethyl acetate and 20 mlof n-butanol are added and the mixture is acidified to pH 2 in the coldwith 1N HCl and washed with water. The organic phase is dried oversodium sulfate and evaporated in vacuo. The oily residue solidifies ontrituration with ether.

Yield: 5.1 g, almost a single compound in the TLC (A).

(e) Z-D-Lys(Boc)-Phe-D-Lys(Boc)-Phe-Gly-NH-(CH₂)₄ -NH-Boc

0.44 g of Boc-NH-(CH₂)₄ -NH₂.HCl, prepared according to Liebig's Ann.Chem. 750 (1971) 165, are added to 1.9 g of the compound obtainedaccording to (d) in 30 ml of DMF, followed by 0.27 g of HOBt, 0.3 ml ofNEM and 0.45 g of DCC, with stirring. After the mixture has been left tostand overnight, the urea has been filtered off and the DMF has beendistilled off in vacuo, the residue is taken up in 60 ml of ethylacetate/n-butanol (1:1) and the mixture is washed, as above, with citricacid solution, bicarbonate solution and water, dried and freed from thesolvent in vacuo. The residue is recrystallized from isopropanol.

Yield: 1.55 g, a single compound in the TLC (A, C).

(f) Z-D-Lys-Phe-D-Lys-Phe-Gly-NH-(C₂)₄ -NH₂.3HCl

582 mg are dissolved in 5.4 ml of HCl/HCOOH analogously to Example 1fand the mixture is worked up as in that example.

Yield: 440 mg, a single compound in the TLC (B, C).

EXAMPLE 8 H-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl (a)Z-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

10.8 g of H-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc. TosOH, prepared from theZ-compound analogously to Example 7b by catalytic hydrogenation inmethanol at pH 4.5, with titration with 1N TosOH, are dissolved in 100ml of DMF, and 4.1 g of Z-Phe-OH, 1.8 g of HOBt, 2 ml of NEM and 3.0 gof DCC are added in succession, with stirring. After the mixture hasbeen left to stand overnight, the urea is filtered off and the DMF isdistilled off in vacuo. The residue is recrystallized from 50 ml of 80%strength ethanol.

Yield: 8.2 g, a single compound in the TLC (A).

C₅₀ H₇₁ N₆ O₉ (900.2).

Calculated: C 66.72, H 7.95, N 9.34. Found: C 66.7, H 7.9, N 9.1.

[α]_(D) ²⁰ : +3.0° (c=1 in 90% strength acetic acid).

(b) H-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH₂.HCl

1.0 g of the compound obtained according to (a) is catalyticallyhydrogenated analogously to Example 7b, but the pH is maintained with 1NHCl in methanol. After analogous working up, 0.92 g of product which isa single compound in the TLC (D) is obtained.

(c) H-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

Splitting off of the Boc protective groups from the compound obtainedaccording to (b) as in Example 1f. Yield: 0.86 g, almost a singlecompound in the TLC (A, B). Aminoacid analysis: Phe:Lys (2.0:1.04).

EXAMPLE 9 Z-Glu-His-Phe-D-Lys-NH-(CH₂)₈ -NH₂.2HCl (a)H-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH

7.5 g of the Z-compound prepared according to Example 8a arecatalytically hydrogenated in methanol and the mixture is worked up,analogously to Example 7b.

Yield: 7.3 g, a single compound in the TLC (D).

(b) Z-Glu(OBu^(t))-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

5.16 g of the compound obtained according to (e) in 70 ml of DMF arereacted with 2.76 g of Z-Glu(OBu^(t))-His-OH, 0.9 g of HOObt, 0.7 ml ofNEM and 1.22 g of DCC and the mixture is worked up analogously toExample 4a. The residue which remains after the ethyl acetate has beendistilled off is triturated several times with ether/petroleum ether(1:1) and dried.

Yield: 5.0 g. According to the TLC (A, C), contaminated with only a verylittle DCU.

(c) Z-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, the Boc and Bu^(t) protective groups aresplit off from 0.5 g of the compound obtained according to (b), and themixture is worked up as described in that example. The product is thendissolved again in a little water, the solution is stirred with a littleweakly basic ion exchanger to pH 4.5 and filtered and the filtrate isevaporated to dryness in vacuo. The residue is triturated with ether anddried. Yield: 0.3 g, almost a single compound in the TLC (A, B).Aminoacid analysis correct.

EXAMPLE 10 Phenylpropionyl-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ NH₂.3CH₃ COOH

Z is split off by catalytic hydrogenation from the Z-peptide preparedaccording to Example 9b. The product is reacted with phenylpropionicacid, DCC and HOBt in a molar ratio and the Boc and tert.-butyl groupsare split off from the reaction product with HCl/HCOOH. After theproduct has been converted into the acetate analogously to Example 1G,the acetate is purified by chromatography on Sephadex.sup.(R) LH 20, asdescribed in that example.

A single compound in the TLC (A, B, C). Aminoacid, analysis correct.

EXAMPLE 11 H-Met(O)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3CH₃ COOH (a)Boc-Met-Glu(OBu^(t))-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

Analogously to Example 7b, 4.2 g ofH-Glu(OBu^(t))-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc. TosOH areprepared from 3.75 g of the compound obtained according to Example 9b.2.56 g of the product in 60 ml of DMF are reacted with 1.2 g ofBoc-Met-ONp, 27 mg of HOBt and 0.4 ml of NEM overnight at roomtemperature, the solvent is distilled off in vacuo and, after digestionwith NaHCO₃ and water, the residue is reprecipitated from ethylacetate/ether, digested with ether and dried.

Yield: 2.2 g, a single compound in the TLC (C).

(b) Boc-Met(O)-Glu(OBu^(t))-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

1.8 g of the compound obtained according to (a) are oxidized with 2 mlof 3% strength H₂ O₂ in 36 ml of acetic acid. After 30 minutes, themixture is concentrated in vacuo and the residue is digested with waterand ether.

(c) H-Met(O)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3CH₃ COOH

Analogously to Example 1f, the crude product obtained according to (b)is freed from the protective groups with 25 ml of HCl/HCOOH. The mixtureis evaporated to dryness in vacuo, the residue is dissolved in 30 ml of50% strength methanol and the solution is treated with the ion exchangerAmberlite® IRA 93 in the acetate form, until the pH value has returnedto about 4.2, filtered and evaporated to dryness in vacuo.

Yield: 1.36 g.

For purification, the product is dissolved in 6 ml of 1% strength aceticacid and chromatographed in the same solvent over a 200×2.5 cm column ofSephadex® LH-20. 480 mg of a chromatographically single peptide with acorrect aminoacid analysis are found in fractions 5 and 6.

[α]_(D) ²⁰ : +4.9° (c=0.5 in 90% strength acetic acid).

290 g of a mixture with the stereoisometric Met(O) derivative are foundin fraction 7.

EXAMPLE 12 H-D-Met(O)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3CH₃ COCH

The procedure is analogous to Example 11, but Boc-D-Met-ONp is used andthe title compound is obtained in corresponding purity afterchromatography on Sephadex® LH-20.

EXAMPLE 13 pGlu-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH (a)pGlu-Glu(OBu^(t))-His-Phe-D-Lys-(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

1.6 of H-Glu(OBu^(t))-His-Phe-D-Lys-Phe-NH-(CH_(s))₈ -NH-Boc. TosOH(Example 11a) and 370 mg of pGlu-OTcp are reacted in 20 ml of DMF in thepresence of 0.17 ml of NEM and 17 mg of HOBt overnight. The solvent isdistilled off in vacuo and the residue is digested with ether.

Yield: 1.6 g.

(b) The crude product obtained under (a) is freed from the protectivegroups analogously to Example 1f, and the product is purified bychromatography analogously to Example 11c. 465 mg of the title compound,which is a single compound in the TLC (C), are obtained. Aminoacidanalysis correct.

EXAMPLE 14 Z-Tyr-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH

1.28 g of the partly protected pentapeptide-amide described in Example11a are reacted in 20 ml of DMF with 610 mg of Z-Tyr(Bu^(t))-ONSu in thepresence of 13.5 mg of HOBt and 0.13 ml of NEM. After the mixture hasbeen left to stand overnight, the solvent is distilled off in vacuo.Analogously to Example 1f, the residue is treated with HCl/HCOOH, aftertrituration with ether. After the solvent has been distilled off, theresidue is chromatographed analogously to Example 11c. Yield of thechromatographically single peptide: 360 mg. Aminoacid analysis correct.

EXAMPLE 15 H-Tyr-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3CH₃ COOH

The procedure according to Example 14 is followed, but 565 mg ofBoc-Tyr(Bu^(t))-ONSu are used, and 280 mg of the title compound areobtained.

A single compound in the TLC (C). Aminoacid analysis correct.

EXAMPLE 16 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl (a)Boc-Met(O₂)-Glu(OBu^(t))-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

0.14 ml of NEM and 150 mg of HOBt are added to 370 mg of Boc-Met(O₂)-OHand 1.4 g of H-Glu(OBu^(t))-HIS-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH in 25 ml of DMF. 242 mg of DCC and, after 30 minutes, a further0.07 ml of NEM are added and, after the mixture has been left to standovernight, it is worked up. The crude product is dissolved in moistethyl acetate, the solution is washed with 10% strength KHSO₄ /K₂ SO₄solution, saturated sodium bicarbonate solution and water in succession,the ethyl acetate solution is dried briefly over sodium sulfate andconcentrated to a small volume and the concentrate is added dropwise toether, with vigorous stirring. Yield of insoluble crude product: 1.1 g.

(b) H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3CH₃ COOH

Analogously to Example 11, 650 g of the compound obtained according to(a) are freed from the protective groups and worked up.

Yield: 520 mg.

350 mg are dissolved in 2 ml of 1N acetic acid and the solution ischromatographed on Sephadex® LH 20 (2.5×100 cm). The main fractionswhich are a single compound in the TLC are collected and lyophilized.

Yield: 230 mg, a single compound in the TLC (C). Amino-acid analysiscorrect.

EXAMPLE 17 Z-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl (a)Z-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

12.7 g of HOBt, 2.84 g of NEM and 4.88 g of DCC are added to 20.85 g ofpartly protected tripeptide (Example 8b) and 4.95 g of Z-Ala-OH in 300ml of DMF, with stirring. After the mixture has been left to standovernight, the DCU is filtered off and the solvent is distilled off invacuo. The residue is precipitated twice from ethanol/water and theproduct is dried in vacuo.

Yield: 18.5 g.

[α]_(D) ²⁰ : -11° (c=1 in 90% strength acetic acid)

C₅₃ H₇₇ N₇ O₁₀ (972.3)

Calculated: C 65.47, H 7.98, N 10.09. Found: C 65.6, H 8.0, N 10.3.

(b) H-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH

16 g of the Z-compound prepared according to (a) are catalyticallyhydrogenated on Pd in methanol/DMF, with the addition of 1N TosOH at pH6. The catalyst is filtered off, the filtrate is clarified with activecharcoal, the solvent is distilled off and the residue is trituratedwith ethyl acetate.

Yield after drying: 12.4 g.

C₅₅ H₈₄ N₈ O₁₂ (1081.35).

Calculated: C 61.09, H 7.83, N 10.36, S 2.9. Found: C 60.9, H 7.8, N10.2, S 3.2.

(c) Z-Glu-(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

2.03 g of Z-Glu(OBu^(t))-OH are added to 5.0 g of the compound obtainedaccording to (b) in 50 ml of DMF, and 675 mg of HOBt, 0.71 ml of NEM and1.13 g of DCC are then added, with stirring. After the mixture has beenleft to stand overnight, the DCU is filtered off, the solvent isdistilled off, the residue is taken up n-butanol/ethyl acetate (1:1) andthe mixture is washed with sodium bicarbonate solution and water anddried over Na₂ SO₄. The residue which remains after the solvent has beendistilled off is digested with ether and dried.

Yield: 5.24 g, a single compound in the TLC (D).

(d) Z-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₆ -NH₂.2HCl

300 mg of the compound obtained according to (c) are treated as inExample 1f to split off the protective groups. After working up, theresidue is triturated with ether and dried.

Yield: 160 mg.

A single compound in the TLC (D). [α]_(D) ²⁰ : -15° (c=1, in MeOH).

Aminoacid analysis correct.

EXAMPLE 18 Z-Ala-Phe-D-Lys-Phe-Nh-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, 1 g of the compound prepared according toExample 17a is treated with formic acid/HCl and the mixture is workedup. Yield: 0.88 g, a single compound in the TLC (A, B).

EXAMPLE 19 H-Met(O₂)-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl (a)Boc-Met(O₂)-Glu(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

344 mg of Boc-Met(O₂)-OH, 137 mg of HOBt, 0.13 ml of NEM and 225 mg ofDCC are added to 1.2 g of theH-Glu-(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH preparedaccording to Example 21a in DMF, and, after initial stirring, themixture is left to stand for 15 hours. The mixture is filtered, thesolvent is distilled off in vacuo and the residue is triturated withwater and ether.

Yield: 1.2 g. The compound still contains a little DCU, but is otherwisea single compound in the TLC (A, d).

(b) H-Met(O₂)-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

Analogously to Example 1f, the compound prepared according to (a) istreated with formic acid/HCl and the mixture is worked up. The productis then dissolved again in water, the solution is filtered and thefiltrate is evaporated to dryness in vacuo. The residue is triturated inethyl acetate and dried.

Yield from 1.0 g: 0.78 g. A single compound in the TLC (A, B, C).

[α]_(D) ²⁰ : -12.5° (c=1, methanol).

Aminoacid analysis correct.

EXAMPLE 20 Methylsulfonyl-β-Ala-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈-NH₂.2HCl (a) Methylsulfonyl-β-alanine

22.3 g of β-alanine are dissolved in 125 ml of 2N MeOH. 20 ml ofmethanesulfonyl chloride and 145 ml of 2N NaOH are simultaneously addeddropwise at 0°-5° C., with vibromixing, and the mixture is vibrated atroom temperature for 3 hours. The solution is extracted with ether andthe extract is diluted to 400 ml and stirred with a strongly acid ionexchanger (Lewatit® S 100) until the pH reaches about 2. The solution isthen evaporated to dryness in vacuo. The residue is taken up in ethylacetate, the mixture is dried over sodium sulfate and DCA is added untilan alkaline reaction is obtained. The precipitate which separates out isfiltered off, washed with ethyl acetate and ether, dried andrecrystallized from tetrahydrofuran.

Yield: 17.4 g of DCA salt, melting point: 156°-157°.

C₁₆ H₃₂ N₂ O₄ S (348.5).

Calculated: C 55.14, H 9.26, N 8.04, S 9.20. Found: C 54.8, H 8.2, N8.0, S 9.4.

To dissociate the salt, it is dissolved in 200 ml of water and thesolution is stirred with a strongly acid ion exchanger until the pHagain reaches 2. The solution can also be filtered over a correspondingexchanger column. The solution is evaporated to dryness in vacuo and theresidue is dried in a desiccator over P₂ O₅ and used in this form. Thecompound is a single compound in the TLC (A, C).

(b) CH₃ -SO₂ -NH-(CH₂)₂-CO-Glu(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

1.2 g of the Z-peptide obtained according to Example 17c arecatalytically hydrogenated according to Example 21a.

Yield: 1.2 g as the tosylate.

The compound is reacted with 204 mg of CH₃ SO₂ -NH-(CH₂)₂ -COOH, 138 mgof HOBt, 0.13 ml of NEM and 225 mg of DCC in 12 ml of DMF and, after themixture has been left to stand at room temperature for 15 hours, the DCUis filtered off and the solvent is distilled off in vacuo. The residueis triturated with water, filtered off and washed with water and ethylacetate.

Yield: 1.1 g. A single compound in the TLC (A, D), a little urea stillvisible.

(c) CH₃ -SO₂ -NH-(CH₂)₂ -CO-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, the protective groups are split off from 0.9g of the compound obtained according to (b).

Yield: 580 mg. Aminoacid analysis correct.

[α]_(D) ²⁰ : -17.6° (c=1, methanol).

EXAMPLE 21 Glutaroyl-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl (a)Glutaroyl-Glu(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂) -NH-Boc

1.2 g of H-Glu(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH,prepared by catalytic hydrogenation of the Z-compound obtained accordingto Example 17c, are dissolved in 10 ml of pyridine. 140 mg of glutaricanhydride are added and the mixture is left to react at room temperaturefor 15 hours. The residue which remains after concentration in vacuo istriturated with ethyl acetate and the solid product is filtered off,washed with ether and dried.

Yield: 1.08 g. A single compound in the TLC (A, B, C).

(b) Glutaroyl-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, 0.9 g of the compound obtained according to(a) is treated with formic acid/HCl.

Yield: 0.6 g.

[α]_(D) ²⁰ : -19.6° (c=1, methanol).

Aminoacid and elementary analysis correct.

The title compound is obtained by dissolving the product in water,treating the solution with a weakly basic ion exchanger to pH 5-6 andconcentrating the filtered solution.

EXAMPLE 22 Z-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl (a)Z-Ala-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

20.85 g of partly protected tripeptide (Example 8b) are reacted with6.53 g of Z-Ala-Ala-OH, 12.66 g of HOBt, 2.84 ml of NEM and 4.9 of DCCin 200 ml of DMF, and the mixture is worked up analogously to Example4a.

Yield: 16.7 g, a single compound in the TLC (C, D).

[α]_(D) ²⁰ : -12.0° (c=1 in 90% strength acetic acid).

C₅₆ H₈₂ N₈ O₁₁ (1043.3).

Calculated: C 64.47, H 7.92, N 10.74. Found: C 64.2, H 8.0, N 10.6.

(b) Z-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, 500 mg of the compound obtained according to(a) are freed from the protective groups. The compound is already asingle compound in the TLC (D) without chromatographic purification.

[α]_(D) ²⁰ : -15.2° (c=1 in 90% strength acetic acid).

C₄₆ H₆₈ Cl₂ N₈ O₇ (916.0).

Calculated: C 60.32, H 7.98, N 12.23, Cl 7.74. Found: C 60.1, H 7.9, N12.1, Cl 7.9.

Aminoacid analysis correct.

EXAMPLE 23 H-Glu-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl (a)H-Ala-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH

Analogously to Example 17b, 16 g of the compound obtained according toExample 22a are catalytically hydrogenated and the mixture is worked up.

Yield: 12.9 g.

C₅₅ H₈₄ N₈ O₁₂ S (1081.35).

Calculated: C 61.09, H 7.83, N 10.36, S 2.96. Found: C 60.9, H 7.8, N10.2, S 3.2.

(b) Boc-Gly-Ala-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

973 mg of the compound obtained according to (a) are reacted with 260 mgof Boc-Gly-ONSu in 10 ml of DHF and, after the solvent has beendistilled off in vacuo, the title compound is isolated by triturationnwith ethyl acetate.

Yield: 850 mg, a single compound in the TLC (D).

C₅₅ H₈₇ N₉ O₁₂ (1066.37).

Calculated: C 61.95 H 8.22 N 11.82. Found: C 61.8 H 8.3 N 11.6.

(c) H-Gly-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

800 mg of the compound obtained according to (b) are freed from theprotective groups analogously to Example 1f.

Yield: 610 mg, a single compound in the TLC (B, D).

[α]_(D) ²⁰ : -24.0° (c=1, in methanol).

C₄₀ H₆₆ Cl₃ N₉ O₆ (875.34).

Calculated: C 54.88, H 7.60, N 14.4, Cl 12.5. Found: C 55.0, H 7.5, N14.2, Cl 12.8.

Aminoacid analysis correct.

EXAMPLE 24 H-Tyr-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

0.97 g of the compound obtained according to Example 17a is reacted with435 mg of Boc-Tyr(Bu^(t))-ONSu in 10 ml of DMF, with the addition of0.13 ml of NEM. Working up is as in Example 13a. The product (0.8 g) isthen freed from the protective groups analogously to Example 1f.

Yield: 0.65 g.

[α]_(D) ²⁰ : -15.0° (c=1, methanol).

A single compound in the TLC (A, B, C).

Aminoacid analysis correct.

EXAMPLE 25 Glutaroyl-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 21a, the partly protected peptide obtainedaccording to Example 23a is reacted with glutaric anhydride, theprotective groups are split off and the mixture is worked up asdescribed.

[α]_(D) ²⁰ : -19.6° (c=1, methanol)

Aminoacid analysis correct.

The product is dissolved in water and the solution is treated with aweakly basic ion exchanger to pH 5-6 to give the monohydrochloride,which is isolated by concentrating the solution and triturating theresidue with ether.

EXAMPLE 26 H-Het(O₂)-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

Analogously to Example 16, the title compound is obtained from thepeptide prepared according to Example 23a, after splitting off theprotective groups.

[α]_(D) ²⁰ : -15.3° (c=1, methanol).

Aminoacid analysis correct. A single compound in the TLC (A, B, C).

EXAMPLE 27 CH₃ NH-CO-(CH₂)₃ -CO-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈-NH₂.2HCl (a) Glutaric acid monomethylamide

6.75 g of methylamine.HCl are suspended in 150 ml of DMF and reactedwith 11.5 g of glutaric anhydride in the presence of 25.5 ml of NEM. Aclear solution is obtained. After the solution has been stirred for 1hour, it is concentrated in vacuo, 120 ml of acetone are added to theresidue and, after filtration, the solvent is distilled off.

The oily residue is extracted with 200 ml+100 ml of ethyl acetate, theethyl acetate solution is filtered and DCA is added until no furtherprecipitate separates out. The precipitate is recrystallized fromisopropanol/ethyl acetate, a first fraction of isopropanol (2 g) beingdiscarded.

Yield: 22 g.

C₁₈ H₃₄ N₂ O₃ (326.5).

Calculated: C 66.22, H 10.50, N 8.58. Found: C 65.7, H 10.3, H 8.5.

The salt is dissociated analogously to Example 20a.

Yield: 7.9 g of oil, chromatographically pure.

(b) CH₃ NH-CO-(CH₂)₃ -CO-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)-NH₂.2HCl

121 mg of HOBt, 0.12 ml of NEM and 200 mg of DCC are added in successionwith stirring to 15 g of the compound prepared according to (a) and 975mg of H-Ala-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH, preparedaccording to Example 23a, in 8 ml of DMF, and the mixture is left tostand at room temperature for 15 hours. Working up is carried outanalogously to Example 17c. TLC (A): a single compound. Yield: 923 mg.The protective groups are split off analogously to Example 1f.

Yield: 790 mg. Elementary analysis correct.

EXAMPLE 28 CH₃ NH-CO-(CH₂)₃ -CO-Glu-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈-NH₂.2HCL

The procedure followed is analogous to Example 27b, but an equimolaramount of H-Glu(OBu^(t))-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH,prepared according to Example 20b, is employed. In the TLC (A, B), thecompound is almost a single compound. Aminoacid analysis correct.

EXAMPLE 29 CH₃ NH-CO-(CH₂)₃ -CO-Glu-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈-NH₂.2HCl

The procedure followed is analogous to Example 27b, but an equimolaramount of H-Glu(OBu^(t))-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH,prepared according to Example 34d, is employed.

EXAMPLE 30 CH₃ NH-CO-(CH₂)₃ -CO-Ala-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈-NH₂.2HCl

The procedure followed is analogous to Example 27b, but the equimolaramount of H-Ala-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH, preparedaccording to Example 37, is employed.

EXAMPLE 31 CH₃ SO₂ -β-Ala-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

975 mg of the partly protected peptide prepared according to Example 23aare reacted with 180 mg of methylsulfonyl-β-alanine analogously toExample 27b, the protective groups are split off as described and themixture is worked up.

Yield: 540 mg. [α]_(D) ²⁰ : -18.5° (c=1, in methanol). Aminoacidanalysis correct. A single compound in the TLC (A).

EXAMPLE 32 Acetylaminocaproyl-Ala-Phe-D-Lys-Phe-NH-(CH₂)hd 8-NH₂.2HCl(a) Acetylaminocaproic acid hydroxysuccinimide ester

26.2 g of ε-aminocaproic acid are suspended in 100 ml of acetic acid.22.2 ml of acetic anhydride are added and the mixture is stirred at roomtemperature for 5 hours. The clear solution is evaporated to dryness invacuo and the residue is digested with ether, filtered off, washed withether and dried in vacuo.

Yield: 30.4 g. C₈ H₁₅ NO₃. Calculated: C 55.47, H 8.73, N 8.09. Found: C55.4, H 8.8, N 8.0.

8.3 g of N-hydroxysuccinimide and 13.2 g of DCC are added to 10.4 g in150 ml of acetonitrile. The mixture is left to stand overnight, the DCUis filtered off and the solvent is distilled off in vacuo. The residueis digested with petroleum ether and diisopropyl ether and dried.

Yield: 16.9 g. This product is used without further purification for thereaction.

(b) CH₃ CO-NH-(CH₂)₅ -CO-Ala-Phe-D-Lys-Phe-NH-(C₂)₈ -NH₂.2HCl

1 g of H-Ala-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₃ -NH-Boc.TosOH, preparedaccording to Example 17b, in 8 ml of DMF is reacted with 0.3 g of theactive ester prepared according to (a), with the addition of 0.5 ml ofNEM, the mixture is left to stand overnight and the solvent is distilledoff in vacuo. The residue is digested with ethyl acetate and water,filtered off and washed with ethyl acetate and ether.

Yield after drying: 0.9 g. A single compound in the TLC (A). Elementaryanalysis correct. The splitting off of the protective groups and workingup are carried out analogously to Example 1f.

[α]_(D) ²⁰ : -18.2° (c=1, in methanol).

EXAMPLE 33 CH₃ SO₂ -NH-(CH₂)₅ -CO-Ala-Phe-D-Lys-Phe-NH-(CH₂)-NH₂.2HCl(a) Methylsulfonyl-ε-aminocaproic acid

Analogously to Example 20a, 65.6 g of ε-aminocaproic acid are reactedwith 40 ml of methanesulfonyl chloride in the presence of 2N NaOH andthe mixture is worked up. The DCA salt is prepared, and 42.3 g ofmelting point 134° are obtained.

C₁₉ H₃₈ N₂ O₄ S (390.6).

Calculated: C 58.43, H 8.81, N 7.17, S 8.21. Found: C 58.2, H 9.9, N7.4, S 8.4.

The acid is liberated according to Example 20a.

Yield: 24.6 l g of oil, which crystallizes completely.

Pure in the TLC (A, B, C).

(b) CH₃ -SO₂ -NH-(CH₂)₅ -CO-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 20, 975 mg of the partly protected peptideobtained according to Example 17b are reacted with 225 mg of thecompound obtained according to (a) to give, after splitting off of theprotective groups and corresponding working up, 724 mg of the titlecompound. Aminoacid analysis correct, almost a single compound in theTLC (A, B).

EXAMPLE 34 H-Met(O₂)-Glu-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH (a)Z-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

3.9 g of Z-Phe-OH and 12.2 g of H-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈-NH-Boc.TosOH, prepared according to Example 9a, are reacted with 1.7 mlof NEM, 1.76 g of HOBt and 2.9 g of DCC in 150 ml of DMF in the mannerdescribed above. After the mixture has been left to stand at roomtemperature for 15 hours, the DCU is filtered off, the solution isevaporated to dryness in vacuo and the residue is recrystallized fromethanol.

Yield: 8.1 g, not quite a single compound in the TLC (A, B, C), but theaminoacid analysis is correct in the context of the limits of error.

(b) H-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH

7.2 g of the title compound are obtained from 8.0 g of the compoundprepared according to (a), after catalytic hydrogenation analogously toExample 7b, and the product is used in this form as achromatographically almost pure starting compound for the followingstage.

(c) Z-Glu(OBu^(t))-Phe-Phe-D-Lys(Bo)-Phe-NH-(CH₂)₈ -NH-Boc

4.0 g of Z-Glu(OBu^(t))-OTcp and 7.6 g of the compound obtainedaccording to (b) are kept in the presence of 0.9 ml of NEM and 100 ml ofDMF for 15 hours. After the solvent has been distilled off in vacuo, theresidue is redissolved from isopropanol.

Yield: 9.0 g. Almost a single compound in the TLC (A, B).

Aminoacid analysis correct.

(d) H-Glu(OBu^(t))-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc.TosOH

4.8 g of product which, in the TLC (A, B) is a single compound, areobtained by catalytic hydrogenation of the compound obtained accordingto (c) analogously to (b) after digestion with ether and water, dryingand reprecipitation from ethanol/ether.

(e) Boc-Met(O₂)-Glu(OBu^(t))-Phe-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ NH-Boc

2.54 g of the compound obtained according to (d) in 50 ml of DMF and inthe presence of 0.26 ml of NEM, 270 mg of HOBt and 440 mg of DCC arereacted with 675 mg of Boc-Met(O₂)-OH analogously to Example 16a and themixure is worked up as described in that example.

Yield: 2.2 g, almost a single compound in the TLC (A, B, C).

(f) H-Met(O₂)-Glu-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂ 2CH₃ COOH

1.9 g of the compound obtained according to (c) are freed from theprotective groups analogously to Example 1f and, analogously to Example11c, the reaction product is converted into the acetate and the acetateis purified by chromatography. After reprecipitation from methanol/ethylacetate, 0.6 g of chromatographically pure (A, B, C) peptide with acorrect aminoacid analysis is obtained.

EXAMPLE 35 H-Met(O₂)-D-Glu-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH

The procedure followed is as described under Example 34, butZ-D-Glu(OBu^(t))-OTcp is used.

EXAMPLE 36 pGlu-His-Phe-D-Lys-phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH (a)pGlu-His-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

0.8 g of pGlu-His-OH and 2.8 g of H-Phe-D-Lys(Boc)-Phe-NH-(CH₂)₈-NH-8oc, prepared according to Example 9a, are dissolved in 50 ml ofDMF. 490 mg of HOObt, 0.4 ml of NEM and 660 mg of DCC are added insuccession and the mixture is stirred at room temperature for 15 hours.The residue which remains after filtering off the DCU and distilling offthe solvent is digested with saturated sodium bicarbonate solution andwater and reprecipitated from methanol/ethyl acetate.

Yield: 1.6 g, almost chromatographically pure (A, C).

(b) pGlu-His-Phe-D-Lys-Phe-NH-(C₂)₈ -NH₂.2CH₃ COOH

The splitting off of the protective groups, conversion into the acetateand chromatographic purification are carried out analogously to Example11c.

Yield: 0.78 g. A single compound in the TLC (A, C), aminoacid analysiscorrect.

EXAMPLE 37 H-Met(O₂)-Ala-Phe-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2CH₃ COOH

The procedure followed is as described in Example 34, but instead ofZ-Glu(OBu^(t))-OTpc, the equimolar amount of Z-Ala-OTcp is employed togive, after splitting off of the protective groups analogously to 1f,conversion into the acetate and chromatography analogously to Example11c, the title compound in chromatographically pure form with a correctaminoacid analysis.

EXAMPLE 38 H-Met(O₂)-Ala-Ala-Ala-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl (a)H-Ala-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-BOC.HCl

The procedure followed is as described in Example 8a, but the Z-Phe-OHis replaced by 3.1 g of Z-Ala-OH. 7.5 g of Z-Ala-D-Lys(Boc)-Phe-NH-(C₂)₈-NH-Boc are obtained, from which the Z group is split off analogously to8b. A single compound in the TLC (C, D), aminoacid analysis correct.

(b) H-Met(O₂)-Ala-Ala-Ala-D-Lys-Phe-NH-(CH₂)₈ -NH₂.3HCl

The compound obtained according to (a) is first reacted withZ-Ala-Ala-OH, DCC and HOBt analogously to Example 22a, the Z group issplit off by catalytic hydrogenation as described above, the product isreacted with Boc-Met(O₂)-OH, DCC and HOBt analogously to Example 16a,and the protective groups are split off analogously to Example 1f. Thetitle compound is almost a single compound in the TLC (A, B), aminoacidanalysis correct.

EXAMPLE 39 H-Met(O₂)-Ala-Ala-Leu-D-Lys-phe-NH-(CH₂)₈ -NH₂.3HCl

The procedure followed is as described in Example 38a, but 3.7 g ofZ-Leu-OH are employed and the subsequent procedure is as described in38b. The title compound is almost a single compound in the TLC (A) andshows the correct aminoacid analysis.

EXAMPLE 40 Z-D-Lys-Phen-NH-(CH₂)₉ -NH₂.2HCl (a)Z-D-Lys(Boc)-Phe-NH-(CH₂)₉ -NH-Boc

Analogously to Example 1c, 27 g of NH₂ -(CH₂)₉ -NH-Boc.HCl, preparedanalogously to Example 1a-b, are reacted with 48 g of Z-D-Lys-Phe-OH andthe mixture is worked up.

Yield: 81.7 g. [α]_(D) ²⁰ : +1.9° (c=1, in methanol). C₄₂ H₆₄ N₅ O₈(767.0). Calculated: C 65.77, H 8.41, N 9.13. Found: C 65.2, H 8.5, N9.0.

(b) Z-D-Lys-Phe-NH-(CH₂)₉ -NH₂.2HCl

The title compound is obtained in the form of a chromatographicallysingle compound (A, B) by splitting off the protective groups from acompound obtained according to (a) analogously to Example 1f. Elementaryanalysis correct.

EXAMPLE 41 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₉ -NH₂.3CH₃ COOH

The Z group is split off from the peptide derivative obtained accordingto Example 40a analogously to Example 8a and the product is then reactedwith Z-Phe-OH as described in that example. The Z group is then splitoff analogously to Example 8b and the further procedure is as describedin Examples 9b and 16a. The protected title compound is obtained, fromwhich the protective groups are split off according to Example 1f.Working up and purification are carried out according to Example 11c.Aminoacid analysis correct.

EXAMPLE 42 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₁₀ -NH₂.3CH₃ COOH

The procedure followed is as described in Examples 40a and 41, but NH₂-(CH₂)₁₀ -NH-Boc.HCl is employed in the first step.

After purification analogously to Example 11c, the title compound ischromatographically a single compound and exhibits a correct aminoacidanalysis.

EXAMPLE 43 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-NH-(CH₂)₆ -NH₂.3CH₃ COOH

The procedure followed is analogous to Example 42, but NH₂-(CH₂)₆)-NH-Boc.HCl is employed as a basic radical.

EXAMPLE 44 H-Met(O₂)-Glu-His-Phe-D-Lys-Gly-NH-(CH₂)₂ -NH₂.3CH₃ COOH (a)Z-D-Lys(Boc)-Phe-Gly-NH-(CH₂)₂ -NH-Boc

According to Example 7d, Z-D-Lys(Boc)-Phe-GlyOMe, prepared according toExample 7a, is subjected to alkaline hydrolysis and the mixture iscorrespondingly worked up. Reaction with NH₂ -(CH₂)₂ -NH-Boc.HClanalogously to Example 1e leads to the title compound.

C₃₇ H₅₃ N₆ O₉ (725.9).

Calculated: C 61.22, H 7.36, N 11.58. Found: C 60.8, H 7.5, N 11.3.

(b) H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-Gly-NH-(CH₂)₂ -NH₂.3CH₃ COOH

The Z protective group is split off from the compound obtained accordingto (a) analogously to Example 41 and the subsequent procedure is asdescribed under Example 41. After purification analogously to Example11c, the title compound is a single compound in the TLC (A, C) andexhibits a correct aminoacid analysis.

EXAMPLE 45 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-Gly-NH-(CH₂)₆ -NH₂.3CH₃ COOH

The procedure followed is analogous to Example 44, but NH₂ -(CH₂)₆-NH-Boc.HCl is employed as the basic amide.

EXAMPLE 46 Phenylpropionyl-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

970 mg of the partly protected peptide obtained according to Example23a, are reacted with 150 mg of phenylpropionic acid analogously toExample 10 to give, after the protective groups have been split offanalogously to Example 1f, 630 mg of the title compound.

[α]_(D) ²⁰ : -18.0° (c=1, in methanol).

A single compound in the TLC in B and D.

EXAMPLE 47 Phenylpropionyl-D-Lys-Phe-NH-(C₂)₈ -NH₂.2HCl (a)Phenylpropionyl-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc

7.5 g of Z-D-Lys(Boc)-Phe-NH-(CH₂)₈ -NH-Boc, prepared according toExample 1e, are catalytically hydrogenated analogously to Example 8aand, analogously to Example 10, the product is reacted with 1.5 g ofphenylpropionic acid and the mixture is worked up.

Yield: 7.9 g. [α]_(D) ²⁰ : +3.2° (c=1, in methanol). C₅₁ H₇₃ N₆ O₈(898.2). Calculated: C 68.21, H 8.19, N 9.36. Found: C 68.0, H 8.2, N9.2.

(b) Phenylpropionyl-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

Analogously to Example 1f, the compound obtained according to (a) isfreed from the protective groups and worked up.

Yield: 7.1 g, a single compound in the TLC (A, B).

EXAMPLE 48 Z-D-Lys-(CH₃)-Phe-NH-(CH₂)₈ -NH₂.2HCl (a)Z-D-Lys(Boc)-(CH₃)-Phe-OCH₃

Analogously to Example 1c, 38 g of Z-Lys(Boc)-OH are reacted with 23 gof N-methyl-L-phenylalanine methyl ester hydrochloride in 500 ml of DMFin the presence of 12.8 ml of NEM and 13.5 g of HOBt with 22 g of DCC atroom temperature. After filtration and removal of the solvent bydistillation in vacuo, the residue is taken up in ethyl acetate and themixture is washed with 10% strength KHSO₄ /K₂ SO₄, sodium bicarbonatesolution and water. After the solution has been dried over Na₂ SO₄, theethyl acetate has been distilled off and the residue has been digested,48.2 g of the title compound are obtained.

Calculated: C 64.85, H 7.44, N 7.56. Found: C 65.0, H 7.3, N 7.5.

(b) Z-D-Lys-(CH₃)Phe-NH-(CH₂)₈ -NH₂.2HCl

The compound obtained according to (a) is hydrolyzed analogously toExample 1d, the resulting dipeptide acid is reacted with the Boc-diamineanalogously to Example 1e and the Boc groups are split off according toExample 1f. Elementary analysis correct. A single compound in the TLC(A, B).

EXAMPLE 49 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-Gly-D-Lys-pyrrolidide.3CH₃COOH

Analogously to Example 1e, Z-D-Lys(Boc)-Phe-Gly-OH, prepared accordingto Example 44a, is reacted with H-D-Lys(Boc)-pyrrolidide, which isobtained by catalytic hydrogenation of the Z compound. The subsequentprocedure is as described in Example 44b, to give the title compoundwith a correct aminoacid analysis.

EXAMPLE 50 H-Met(O₂)-Glu-His-Phe-D-Lys-Phe-Gly-Lys-diethylamide.3CH₃COOH

The procedure followed is analogous to Example 49, butH-Lys(Boc)-diethylamide is employed. The title compound purifiedaccording to Example 11c is a single compound in the TLC (A, B) andexhibits a correct aminoacid analysis.

EXAMPLE 51 CH₃ CO-β-Ala-Ala-Ala-Phe-D-Lys-Phe-NH-(CH₂)₈ -NH₂.2HCl

The procedure followed is analogous to Example 31, but the amount ofacetyl-β-aniline equivalent to the partly protected peptide preparedaccording to Example 23a is employed. The title compound is obtained,with a correct aminoacid analysis.

EXAMPLE 52 ##STR1##

The procedure followed is analogous to Examples 31 and 51, but4-methylsulfonylbenzoic acid is used as the reactant. S:N ratio correct.

We claim:
 1. A pharmaceutical composition comprising an effective amountof a compound of the general formula I

    R.sup.4 -A.sup.5 -A.sup.6 -R.sup.7                         (I)

in which: R⁴ denotes benzyloxycarbonyl (Z), (C₂ -C₆)-alkanoyl, (C₆-C₁₀)-aryl-(C₂ -C₄)-alkanoyl or cycloalkanoyl with up to 2 alkyl and 5-7cycloalkyl carbon atoms, bonded via Nα, or R³ -A⁴, in whichA⁴ isselected from the group consisting of Ala, Val, Leu, Ile, Met, Ser(C₁-C₆ -alkyl), Thr (C₁ -C₆ -alkyl), Cys(C₁ -C₆ -alkyl), Phe,C-phenylgycine and Tyr(C₁ -C₆ -alkyl) and R³ represents hydrogen, Z, (C₂-C₆)-alkanoyl, (C₆ -C₁₀)-aryl-(C₂ -C₄)-alkanoyl or cycloalkanoyl with upto 2 alkyl and 5-7 cycloalkyl carbon atoms, bonded via Hα, or R² -A³-A⁴, in whichA⁴ is as defined above, A³ denotes His, Ala, Phe or D-Lysand R² is defined as R³, or represents (C₂ -C₄)-alkanoyl-ω-amino-(C₅-C₈)-n-alkanoyl, methylsulfonyl-ω-amino-(C₅ -C₈)-n-alkanoyl,4-methylsulfonylbenzoyl, succinoyl or glutaroyl, bonded via Hα, or R¹-A² -A³ -A⁴, in whichA³ and A⁴, are as defined above, A² representspyroglutamyl, Glu, D-Glu or Ala and R¹ is defined as R², or represents(C₂ -C₄)-alkanoyl-ω-amino-C₃ -C₄)-n-alkanoyl, methylsulfonyl-ω-amino-(C₃-C₄)-n-alkanoyl, methylamido-glutaroyl, H-Met, H-D-Met, H-Met(O),H-D-Met(O), H-Met(O₂), H-D-Met (O₂), H-Gly, Z-Gly, H-Tyr, Z-Tyr orpyroglutamyl, bonded via Nα, A⁵ denotes D-Lys or Lys, A⁶ denotes theradical of phenylalanine, N-methylphenylalanine, 4-(C₁-C₄)-alkoxyphenylalanine or 1,2,3,4-tetrahydroisoquinoline-3-carboxylicacid and R⁷ denotes NH-(CH₂)_(n) -NH₂, Gly-NH-(CH₂)_(m) -NH₂, Gly-Lys-R⁸or Gly-D-Lys-R⁸, in which n represents an integer from 4 to 10, mrepresents a integer from 2 to 6 and R⁸ represents 1-pyrrolidinyl,1-piperidinyl, NH-R or NR₂, where R=(C₁ -C₄)-alkyl,or one of itsphysiological acceptable salts, and a physiological acceptable carrier.2. A method of improving learning and memory performance, byadministration of a pharmaceutical composition as claimed in claim
 1. 3.A method of treating post-traumatic and degenerative brain damage byadminsitering a pharmaceutical composition as claimed in claim
 2. 4. Apharmaceutical composition having mood-lightening, antidepressant andanxiolytic properties comprising a pharmaceutically effective amount ofa compound as claimed in claim 1.